'''
Mission 6: Heartbeat
Mild Remix - 1st option
Changes the heart images to blinking pixels
 -- This solution uses all four pixels and two colors
    Students can use 1-4 pixels and 1 color (plus black) 
       or two or more colors
'''
from codex import *
from time import sleep

delay = 1

while True:
    # one heartbeat
    pixels.set(0, GREEN)
    pixels.set(1, GREEN)
    pixels.set(2, GREEN)
    pixels.set(3, GREEN)
    sleep(delay)
    pixels.set(0, YELLOW)
    pixels.set(1, YELLOW)
    pixels.set(2, YELLOW)
    pixels.set(3, YELLOW)
    sleep(delay)

    if buttons.was_pressed(BTN_A):
        delay = delay + 0.2

    if buttons.was_pressed(BTN_B):
        delay = delay - 0.2